130 U.S. NATIONAL MUSEUM BULLETIN 271 



Key to the Genera of Ampeliscidae 



1. Pereopod 5: anterior edge of posterior lobe on article 2 lacking setae near its 



junction with article 3 (fig. 581) 2 



Pereopod 5: anterior edge of posterior lobe on article 2 bearing setae up to 

 its junction with article 3 (figs. 58m,n,o) 4 



2. Flagella of antennae poorly developed, with 2 to 4 articles (fig. 576) [antero- 



ventral corner of head produced (fig. 576)] Byblisoides 



Flagella of antennae long, usually with more than 10 articles [anteroventral 

 corner of head rarely produced] 3 



3. Anteroventral corner of head produced Triodos 



Anteroventral corner of head sloping, unproduced Ampelisca 



4. Posterior lobe of article 2 on pereopod 5 strongly expanded distally, posterior 



edge oblique (fig. 58m) Byblis 



Posterior lobe of article 2 on pereopod 5 not expanded distally, posterior edge 

 vertical (figs. 58n,o) Haploops 



Genera of Ampeliscidae 



Ampelisca Kr0yer 



Ampelisca Kr0yer, 1842. — Stebbing, 1906. 

 Pseudophthalmus Stimpson, 1853. 

 Araneops Costa, 1853c, 1857. 

 Tetromatus Bate, 1856, 1857a, 1857c. 



Type-species: A. eschrichtii Kr0yer, 1842 (monotypy). See Sars, 

 1895. 



Pereopod 5 with posterior lobe of article 2 greatly expanded distally, 

 posterior edge oblique, anterior edge of posterior lobe lacking setae 

 near its junction with article 3; palp article 3 of mandible variable in 

 length; antenna 2 with more than five flagellar articles; anteroventral 

 corner of head unproduced. Species: 94, primarily littoral cosmo- 

 politan, about 20 bathyal and one abyssal species. 



Byblis Boeck 



Byblis Boeck, 1871.— Stebbing, 1906. 



Type-species: Ampelisia (lapsus) gaimardii Kr0yer, 1846 (mono- 

 typy)- See Sars, 1895. 



Pereopod 5 with posterior lobe of article 2 greatly expanded distally, 

 posterior edge oblique, anterior edge of posterior lobe bearing setae 

 near its junction with article 3; palp article 3 of mandible shorter 

 than article 2; antenna 2 with more than five flagellar articles; antero- 

 ventral corner of head unproduced. Species: 21, cosmopolitan, 

 littoral to abyssal. 



